AC and SC, Scapula & Shoulder Girdle review Flashcards
Describe the acromioclavicular joint
- where acromion process of scapula is meeting up with lateral end of clavicle (ALWAYS indicate which side! Diff movements and form 2 diff joints)
- common place for injuries (separated shoulder)
Describe the joint and articular surfaces of the AC joint
- joint surfaces of acromion process lateral end of scapula are small, very shallow
- flat & shallow = not a lot of ROM because big idea is to hold scapula that clavicle
- on the inside we find a articular disk just like SC joint: fibrocartilaginous disk sandwiched between the 2 ends of the bones
What ligaments hold the AC joint together?
AC (acromioclavicular) ligament, CC ligaments (coracoclavicular)
Describe the AC ligament
- reinforces The joint capsule and is thickest on the superior side of the joint
- not strongest stabilizer of joint
Describe the coracoclavicular ligaments
- attaches down to coracoid process
- a pair of ligaments
CONOID: medial side, coming up from the coracoid process to the conoid tubercle, to inferior aspect of clavicle
TRAPEZOID: off coracoid process, runs along trapezoid line on the inferior aspect of the clavicle. Helps prevent superior translation of the lateral end of the clavicle, keeping the AC joint together - The two ligaments help hold scapula up relative to lateral end of clavicle
Describe the coraco-acromial ligament
- doesn’t actually support a joint directly, just nearby AC joint
What effect does gravity have on AC joint ligaments?
- gravity wants humerus to go down
- scapula will also go down & coracoid process away from clavicle, stretches these ligaments
Describe the location and function of SC (sternoclavicular) joint
- medial end of the clavicle fits into concave spot on manubrium of sternum
- has a very important job! Gets lots of motion here that pivot off SC joint
ELEVATION
DEPRESSION
PROTRACTION
RETRACTION
What does the magnitude of actions @ SC joint mean for it’s ligaments?
We need lots of ligamentous support to keep joint stable
Name the ligaments and structure (s) that keep the SC joint together
- anterior SC ligament
- posterior SC ligament
- costo-clavicular ligament
- articular disk
Describe the SC articular disk
- similar to meniscus in knee, sandwiched between 2 bones and made up of fibrocartilage
- deals with compressive forces through the joint & shearing or frictional forces that occur there as well
- inside of joint capsule (that every synovial joint will have)
The SC joint capsule is reinforced by _
2 SC ligaments
Describe the anterior SC ligament
- comes from anterior side of the manubrium of the sternum
- comes up and lands on medial end of clavicle
Describe the posterior SC ligament
- does the same thing as anterior SC and has same attachments, just more posterior
Describe the costo-clavicular ligament
- named for it’s attachments
- comes in off superior aspect of costal cartilage on 1st rib
- travels superiorly to attach a long inferior side of the medial end of the clavicle